Feb.7 (GMM) Bernie Ecclestone has summoned the chiefs of F1's smallest teams to his London headquarters.

Germany's Auto Motor und Sport said representatives of Marussia, Caterham, Force India, Sauber and Toro Rosso have been invited to the meeting on Thursday.

With HRT now folded and other small teams ousting salaried drivers in favour of 'pay drivers' for 2013 and worrying about the cost of buying an engine in 2014, the meeting follows speculation F1's smallest teams are buckling under the pressure of financial problems.

"The situation is serious," said German correspondent Michael Schmidt.

Mercedes boss Ross Brawn, however, said he is not concerned.

"We have always had these phases, and formula one has always found its way out of them," he is quoted as saying.

Referring, however, to Thursday's meeting with Ecclestone, journalist Schmidt continued: "There is much to discuss.

"It's quite possible he (Ecclestone) will remind them of an old idea: throughout the paddock the words 'customer car' are doing the rounds again."